Track-type work vehicles, such as bulldozers, have a crawler type carrier. The crawler type carrier has a crawler belt apparatus, a sprocket wheel, an idler tumbler, a roller device, and the like. The crawler belt apparatus is generally structured by coupling a plurality of crawler belt links endlessly with pins and bushings and attaching a track shoe plate to the plurality of crawler belt links. The crawler belt apparatus is wound around the sprocket wheel, the idler tumbler and the roller device, and is configured to be rotationally driven with a rotation of the sprocket wheel by engaging the tooth of the sprocket wheel with the above-mentioned bushings.
The roller device has a shaft, a seal, a roller shell, and the like. The shaft is fixed to a vehicle. The shaft has a storage for lubricating oil, and is provided with the seal for sealing the device such that lubricating oil does not leak out. The roller shell is rotatably supported by the shaft. The above-mentioned lubricating oil is supplied to the rotating section of the roller shell and the shaft. The roller shell is worn by rolling over rail surfaces of the crawler belt links during traveling. As the wear of the roller shell progresses, the roller shell needs to be replaced. When replacing the roller shell, there is a technique for replacing the whole roller device. However, this technique is costly. Therefore, a technique for replacing the roller shell alone rather than the whole roller device has been proposed. This technique for replacing the roller shell alone rather than the whole roller device is disclosed in, for example, Japanese Patent Laying-Open No. 50-90026 (PTD 1).